Wednesday, October 20, 2010


We all have heard of GSM and CDMA networks. But do we know what they mean and stand for. What are the major differences between the two?

GSM: Global System for Mobile Communications: 80% of the telecom market across the globe use GSM network. In India, Vodafone, Airtel, Aircel, Idea, TATA docomo, Reliance GSM are the important GSM providers

CDMA: Code division multiple access: MTS, Reliance, TATA

The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM.

CDMA standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in India as CDMA networks make progress in other parts of the world.

There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other.

To an end user, the architecture doesn’t really matter. The end result does.

Subscriber Identity Module (SIM) cards:

GSM phones use SIM cards. The removable SIM card allows phones to be interchanged & upgraded without carrier intervention. The SIM itself is tied to the network, rather than the actual phone.

CDMA networks use a R-UIM card. CDMA operators sell handsets that are linked to one their network only and are not card-enabled. To upgrade a CDMA phone, the telecom operator must deactivate the old phone then activate the new one. The old phone becomes useless.

Data Transfer Speed: Now mobile phones are used for not only making calls but as streaming video devices & email devices. Speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards.

EVDO(Evolution- Data Only), also known as CDMA2000, is CDMA's answer to the evergrowing need for speed with a downstream rate of about 2 megabits per second. However in reality the speed is somewhere between 300-700 kilobits per second (kbps). This is comparable to basic cable.

GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps. In reality the speed is between 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required. I will touch upon UMTS and HSDPA later.

Both require being within close range of a cell to get the best speeds, while performance decreases with distance.

National Roaming: Most of the telecom operators today such as Vodafone, Airtel, Idea, Aircel, TATA have coverage in all 23 circles. These operators tie-up within themselves (Aircel Mumbai with Vodafone Maharashtra & Goa) allowing coverage in areas where they themselves have weaker network coverage.

CDMA networks may not cover rural areas as well as GSM networks, and though they may contract with GSM cells for roaming in more rural areas, the charge to the customer will generally be significantly higher.

International Roaming: If you need to make calls to other countries, a GSM network can offer international roaming, as GSM networks dominate the world market. If you travel to other countries you can even use your GSM cell phone abroad, providing it is a quad-band phone (850/900/1800/1900 MHz).

By purchasing a SIM card with minutes and a local number in the country you are visiting, you can make calls from that local card to save yourself international roaming charges from your network back home. CDMA phones that are not card-enabled do not have this capability, however there are several countries that use CDMA networks.

According, CDMA networks support over 270 million subscribers worldwide, while tallies up their score at over 1 billion.

Please note now CDMA users can switch between CDMA operators and keep the same phone.

A total of 391.76 wireless subscribers were split between 12 wireless telecom operators. Bharti Airtel lead the way with 93.92 million followed by Reliance (GSM + CDMA). Sistema which launched its services few months back has 0.39 million subscribers (3.9 lakh).

Top 12 Wireless Operators in the country :


Wireless Group

Subscriber base in millions

Market share (%)

















































Market share of top 12 operators :

Of the 391.76 wireless subscribers GSM has a market share of 76% and here is how they are split :

Reliance has registered a 6.73 % market share which is quite impressive for service which was launched only 6 months ago.

CDMA subscribers are at 94.5 million and here is how they are split :

Tata Teleservices which launched its GSM operations under brand name Tata DoCoMo will be another player to look out for in this next few quarters. Swan Telecom and Unitech Wireless are 2 other operators which are gearing up for a launch.

Reliance rules CDMA followed by Tata Teleservices (Tata Indicom). Shyam telelink is now rebranding to MTS India. CDMA doesn’t look as much over-crowded as GSM but when put together the overall picture of Indian telecom looks crowded with 12 operators and 3 waiting in the wings. Reliance and Tata are the 2 companies to watch out for with the dual play of GSM and CDMA operations.

The average revenue per user of CDMA is 99 rupees and that of GSM is 205 rupees. With 3 new players coming in for GSM the ARPU’s will come down. CDMA which is supposed to be a better network for data access can use this opportunity to increase the ARPU’s and subscribers. They just have to sort out the handset availability issue.

Source : TRAI

So which network do you use? CDMA or GSM?


  1. GSM! Been on Vodafone as far as I can remember! Interesting post btw :)

  2. CDMA(Code Division Multiple Access) is a digital cellular technology that uses spread-spectrum techniques.CDMA consistently provides better capacity for voice and data communications than other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built.It doesn't have sim card.
    The reason for more GSM usage is that the international Roaming of GSM is Very good and it has sim card,So you can easily swap your sim card when you need.If we got a locked phone means we can unlock it by getting the unlocking service from any one of the online service provider like